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Topic Review (Newest First)

02-29-2008 12:46 PM

sailingdog

HS-

I want to get a Mr. Fusion for my boat... a lot lighter than all those pesky batteries..... and only a little radiation to worry about.

02-29-2008 12:29 PM

hellosailor

SD-
I figured, if they used lag bolts and blew themselves up at the dock, I could save them from a painful slow death at sea, so I'd really be doing them a favor, right?

Actually the problem with breakers welding, is that if you drop a wrench across the cables, or something chafes through and grounds, THAT'S when you get get the dead short close enough to the battery to pull 3500+A and weld a breaker. I learned that while I was shopping for breakers, and one of the nice folks who makes them told me "Uh, you really want a fuse for that". Go figure.

Now, if you use really big LONG lag bolts and an air hammer to install them, you can skip those pesky extra battery hold-down straps, and just bolt the whole thing to the outer hull in one shot, can't you?

This is why WalMart stopped selling them home knee-you-clee-er hot water heaters with the rotissery spit attachments, isn't it?

02-29-2008 07:25 AM

sailingdog

Yes, but they have to be really short lag bolts... HS, you're s a sick and twisted puppy... I can see someone winning a darwin award cause they tried to mount something to the battery case from reading what you wrote... there are some awfully dumb people out there.

Good point about the breaker... I don't know what the surge limit on it is. The situation we were using it in, the surge wasn't really a major concern. The battery wasn't ever going to be used for starting the boat through that wire, since it was a windlass battery, and that was on the wiring going back to the main electrical system for charging the windlass battery. Since it was connected by an ACR unit, and not directly hooked up to the main electrical system, there's never going to be more than 100 amps going through the breaker.

BTW, according to the BlueSea site, those breakers I pointed out are good for up to 3000 Amps surge.

Those fuse blocks sd posted, can be mounted directly on the battery with size 00 lag bolts, right into the side of the case and through the plates.

KIDDING!

But Scotch exterior-grade double-sided tape, or hot melt glue, or a good adhesive caulk, or the self-adhesive industrial strength velcro, will all make reasonable alternatives. Or you can mount them to a small plate, make a 3/4" hole in it, and let the battery terminal itself stick up through the hole to "anchor" the plate. All sorts of ways.

SD, unless that breaker is one of the special ones that can carry a 5000A surge without fusing shut--it isn't for battery primary service. The conventional breakers all arc shut (useless) with loads around 3500A, and a good battery can put that out into a dead short. The good breakers are damn closed to $100 each.

02-29-2008 01:04 AM

Classic30

Something else to keep in mind:

When installing fuses/circuit breakers/whatever near the batteries, please make sure there are no flammable materials (wood, fibeglass, rubber) within several inches of the wiring - when a fuse blows, lots of heat (and sometimes molten metal) is produced... and we don't want the boat catching fire now, do we?

02-29-2008 12:32 AM

sailboy21

I, for one, think the schematic posted looks just about right for a small boat. The only comments I have, is 10AWG wire is pretty big, probably not necessary for loads from your 30 amp panel. My boat has a refer, 12 cabin lights, 2 water pumps, 2 blowers, radar, gps, VHF and I have never exceeded even 20 amps from the main panel. I do have other loads that bypass the panel, SSB (20 amps at full output) and 3 bilge pumps that skip my panel and are fused/breakerd independently from the ammeter and panel. This is obviously not a panel for an energy intensive boat.. therefore 4 gage (160 amps max) seems more than adequate for two house banks which are likely nor more than groups 31(???), and 10 AWG wire should be about twice what would be required to safely blow your panels fuse... just a thought. Heavy wire is expensive and hard to run.. I am more than comfortable used 14 or even 16 AWG for my cabin lights no lost sleep for me!

02-29-2008 12:08 AM

hellosailor

Those fuse blocks sd posted, can be mounted directly on the battery with size 00 lag bolts, right into the side of the case and through the plates.

KIDDING!

But Scotch exterior-grade double-sided tape, or hot melt glue, or a good adhesive caulk, or the self-adhesive industrial strength velcro, will all make reasonable alternatives. Or you can mount them to a small plate, make a 3/4" hole in it, and let the battery terminal itself stick up through the hole to "anchor" the plate. All sorts of ways.

SD, unless that breaker is one of the special ones that can carry a 5000A surge without fusing shut--it isn't for battery primary service. The conventional breakers all arc shut (useless) with loads around 3500A, and a good battery can put that out into a dead short. The good breakers are damn closed to $100 each.

By the way I checked it out and the Alden Trull site only opens correctly in Internet Explorer and another browser called Enigma. I doesn't work right in Mozilla, Netscape, Opera or Safari.

02-28-2008 10:20 PM

sailingdog

Peter-

Glad to help out.

Basically, if the wires are protected by conduit, loom, sheathing or some other way, the fuse/circuit breaker can be further away, since the wire isn't likely to get cut and shorted out.

02-28-2008 10:16 PM

peikenberry

As for the distance overcurrent protection must be from the source of power, remember the overcurrent protection is there to protect the wire, not the equipment. So it needs to be close to the source. There is an exception. If the wire is contained in a loom, conduit, or sleeve (insulation doesn't count as a sleeve) it can be up to 40 inches away. Here's what both the regulation and ABYC standard says: "If it is physically impractical to put the fuse or circuit breaker within seven inches of the source of the power it can be up to 40 inches (101.6 cm) away, if the wire is contained for it's entire length between the source of power and the circuit breaker, in a sheath or an enclosure."